Muffler construction



July 26, 1966 c. E. NORDQUES'T ET A]. 3,262,189

MUFFLER CONSTRUCTION Original Filed Oct. 11, 1961 4 Sheets-Sheet 1 if a ,3; IN VENTORS Car) f. Wordauesf 2770/1 12? 0. Ross BY gum THE [R ATTORNEY y 6, 1966 C. E. NORDQUEST ET AL 3,

MUFFLER CONSTRUCTION 4 Sheets-Sheet 2 Original Filed 001:. 11, 1961 July 26, 1966 c. E. NORDQUEST ET AL 3,262,139

MUFFLER CONSTRUCTION Original Filed Oct. 11, 1961 4 Sheets-Sheet 5 INVENTORS Car) [I flordaues') man/z)? 0. Ross TAKE/R A 7'7'0RNEV y 1966 c. NORDQUEST ET AL 3,262,189

MUFFLER CONSTRUCTION 4 Sheets-$heet 4 INVENTORS Car! it floraaues? 2W0) w'n 0. Ross BY THE/R ATTOR/Vfy Original Filed Oct. 11, 1961 United States Patent 3,262,189 MUFFLER CONSTRUCTIGN Carl E. Nordquest and Marvin 9. Ross, Dayton, Ohio, assignors to General Motors Corporation, Detroit,

Mich, a corporation of Delaware ()riginal appiication Oct. 11, 1961, Ser. No. 144,355.

Divided and this application Dec. 30, 1964, Ser. No. 422,381

2 Claims. (Cl. 29--157) This application is a division of copending application, Serial No. 144,355, filed October 11, 196 1.

This invention relates to mufliers and to the method of making mufliers for use on automobiles and the like.

It is an object of this invention to construct a muffier that the parts can be coated with porcelain and inspected for imperfections in the porcelain coating prior to final assembly.

A further object of this invention is to provide a basic muifler design which makes it possible to utilize identical basic parts in constructing a large number of different mufllers capable of mufiling a wide range of noise frequencies.

Another object of this invention is to provide a muffler construction in which parts of the muffler are coated with porcelain prior to final assembly and in which chipping of the porcelain within the muffler during final assembly is avoided.

Still another object of this invention is to provide a two-part muffler having a flanged joint in which the angle of the flange reduces the tendency for splitting open the seam in the event of a backfire.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein preferred embodiments of the present invention are clearly shown.

In the drawings:

FIGURE 1 is a vertical sectional view taken substantially on line 11 of FIGURE 2.

FIGURE 2 is a plan view of the bottom half of the muffler showing the sound attenuating baffles in place.

FIGURE 3 is a sectional view taken substantially on line 33 of FIGURE 2 showing the construction of the bottom portion of the muflier housing.

FIGURE 4 is a side elevational view showing one of the sound attenuating baflles.

FIGURE 5 is an end view of the same bafile.

FIGURE 6 is an enlarged fragmentary sectional view showing the details of construction of one of the tabs on the bafiies.

FIGURE 7 is a fragmentary sectional view taken on line 77 of FIGURE 1.

FIGURE 8 is a plan view of the muflier cover.

FIGURE 9 is a sectional view of the cover taken substantially on line 99 of FIGURE 8 showing the cover prior to its attachment to the rnuflier housing.

Referring now to the drawings wherein a preferred embodiment of the invention has been shown, reference numeral 10 designates the bottom portion of a two-part muflier housing. This bottom portion is in the form of a drawn shell element having a peripheral flange 12 which forms an acute angle of approximately seventy-five degrees with the side wall of the drawn shell element 10. The open side of the drawn shell element 10* is closed by means of a cover element 14 having a flange portion 16 which is wrapped around the flange 12, as best shown in FIGURE 1 of the drawings. By virtue of this angular relationship, the tendency for the anufiler to split open at the seam in case of a backfire is greatly reduced.

A plurality of baffles 20, 22, 24 and 26 are disposed within the drawn shell element 10, as best shown in ice FIGURE 2 of the drawings. The number of baffles and the spacing of the baffles can be varied to meet the requirements of any given engine exhaust system. The side walls of the drawn shell 10 are provided with a plurality of corrugations or guide slots 28 which serve to position the bafiies. The edges of the baffles are also spot welded to the sides and bottom of the shell element 10 so as to be held firmly in place. Since each mufller must be designed to match a given internal combustion engine and since minor changes in the design of an internal combustion engine materially affect the muffler construction required for properly mufiiing the noises generated by the engine, it is important to provide means for varying the construction and arrangement of the baflles within the main muffler housing without the need for making any major changes in the mulfler. In the arrangement shown in the drawings, the corrugations 28 serve as a convenient means for positioning the transversely extending baffles in any one of many different locations with the result that the same drawn shell can be used in conjunction with a large number of different engine designs. With this construction the same basic tools can be used in manufacturing a large number of different muffler designs.

Various muffler tubes 30, 32, 34 and 36 are disposed within the main mufiier body and each of these tubes has its one end permanently secured to one of the transverse extending baffles. Thus, tube 34, for example, has its one end secured to the baflle 24. The tube has its one end secured to the baflle 20 and has its other end merely extending into a flange portion 38 formed on the baffle 22 but does not need to be secured to the baffle 22. The tube assembly 36 is permanently secured to one of the baffles, such as the baffle 24, and projects freely through openings in the other baffles through which it projects. By virtue of this arrangement, it is readily apparent that the locations of the baffles 20', 22, 24 and 26 can be varied considerably without changing the construction of these bafiles and without changing the construction of the drawn shell element 11%. It is recognized that the length of the tubes 30, 32, 34 and 36 may have to be varied for different engine designs but this can be done without requiring any major tool changes.

As best shown in FIGURES 7 and 8, the cover element 14 is provided with a plurality of apertures 40 which are adapted to receive projecting tab elements 42 for-med adjacent the one edge of each of the transversely extending baffles 29, 22, 24 and 26. FIGURES 4 and 6 show how the ends of the tab elements 42 are beveled at 44 and 46 so as to facilitate assembly of the cover 14 onto the tabs 42. Each tab is reduced in thickness by score lines as indicated at 47 whereby the tabs can be bent at this point without injury to the main porcelain coating which is applied to the muffler parts after the baffles have been secured in place but before the cover 14 is attached to the bottom shell or housing element 10.

It has been found desirable to porcelain coat all portions of the muffler which are exposed to the products of combustion. While it is recognized that it is old to use porcelain to coat the interior surfaces of a mufiier, the big problem has been that of providing a satisfactory muffier construction and enameling technique which will insure complete coating of all of the muflier parts. The complicated nature of the internal muffler passages and chambers makes it very diflicult, if not impossible, to properly coat the interior of the muflier with porcelain after the muffler has been closed. It has been customary to pour the ingredients for the porcelain coating into the interior of a completely assembled muffler and to slosh it around in an attempt to coat all of the complex internal surfaces of the mufiier but it has p-roven to be very difficult and impractical to completely cover all of the internal surfaces.

In applicants muffler construction, the porcelain coating is applied to the bottom portion of the muffler housing after the bafiies have been assembled therein but before the cover 14 is placed thereon. This not only makes it possible to better coat the interior surfaces of the element and the various baflies disposed therein but it also makes it possible to inspect the procelain job before the cover 14 is assembled onto the drawn shell portion. The cover 14 is also coated with porcelain before it is fastened in place. A representative method of porcelain coating is disclosed in Pat. No. 3,093,208 issued June 11, 1963. After the parts have thus been coated with porcelain, the cover 14 is secured to the main housing element 10 by bending the tabs 42 along the score lines 47 and by bending the flange 16 of the cover around the flange 12 of the main housing or shell 10. Adjacent tabs are preferably bent in alternate directions. As best shown in FIGURE 7 of the drawings, a strip of asbestos 50 and a metal strip 52 are arranged over the row of perforations through which the tabs 42 project. The score lines 47 limit the area over which the porcelain coating is damaged when the tabs 42 are bent. Since these tabs 42 extend through the cover element 40, the asbestos strip 50 and the metal strip 52, it is obvious that no part of the associated bafile which is located within the muffler chamber has any damage done to the porcelain. Since that portion of the tabs which projects to the outside of the rnuflier housing are disposed on the top side of the muflier, they are largely protected from the elements which would tend to cause destructive rusting. In order to further protect the tabs from damage, a coating 54 of silicon powder and water glass is sprayed onto the top surface of the muflier The bottom surface of themufller housing element 10 is protected from damage by gravel, etc., which might be thrown against the muffler by means of a stainless steel cover which is provided with a flange construction 62 adjacent its upper edge which is wrapped around the flange joint formed between the cover element 14 and the housing element 10, as best shown in FIGURE 1 of the drawings. An intermediate layer of asbestos 63 is disposed between the housing element 10 and the stainless steel cover 60 so as to insulate the cover 60 from the housing element 10. Sealing compound 64 is provided at the edge of the flange 62 so as to prevent moisture from entering the space between the cover 60 and the housing element 10. This sealing compound can be any well known heat resistant sealing material, such as a silicon sealing compound.

While the embodiments of the present invention as herein disclosed constitute preferred forms, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. The method of manufacturing a porcelain coated muifier which comprises forming an assembly including a hollow shell having disposed therein transverse baflles having an edge provided with a plurality of cover securing tabs directed outwardly of the edge, providing each of the tabs with a reduced cross section across the width thereof adapted to be bent towards the edge to secure the cover on the shell, porcelain coating the interior of said shell and the surfaces of said baffies, including the tabs, providing a perforated cover, porcelain coating the perforated cover and thereafter attaching said porcelain coated cover to said shell by passing said tabs through the perforations in said cover and then bending the tabs along the reduced cross section over onto the cover so as to hold said cover in place relative to said baffles.

2. In the method of claim 1, the step of placing an auxiliary sealing member on the perforated cover to surround the tabs, prior to bending the tabs, whereby as the tabs are bent they are forced against the auxiliary sealing member to secure it to the cover and against the tabs.

References Cited by the Examiner UNITED STATES PATENTS 1,810,252 6/1931 Noonan.

1,869,419 8/ 1932 Hamilton.

2,229,526 1/1941 Schabaker.

2,560,290 7/1951 Helberg 29513 2,703,635 3/ 1955 Carlson 29513 3,093,208 6/1963 Howe 29157 3,127,951 4/1964 Pierce 29157 FOREIGN PATENTS 1,181,590 6/1959 France.

JOHN F. CAMPBELL, Primary Examiner.

WHITMORE A. WILTZ, Examiner.

P. M. COHEN, Assistant Examiner. 

1. THE METHOD OF MANUFACTURING A PORCELAIN COATED MUFFLER WHICH COMPRISES FORMING AN ASSEMBLY INCLUDING A HOLLOW SHELL HAVING DISPOSED THEREIN TRANSVERSE BAFFLES HAVING AN EDGE PROVIDED WITH A PLURALITY OF COVER SECURING TABS DIRECTED OUTWARDLY OF THE EDGE, PROVIDING EACH OF THE TABS WITH A REDUCED CROSS SECTION ACROSS THE WIDTH THEREOF ADAPTED TO BE BENT TOWARDS THE EDGE TO SECURE THE COVER ON THE SHELL, PORCELAIN COATING THE INTERIOR OF SAID SHELL AND THE SURFACES OF SAID BAFFLES, INCLUDING THE TABS, PROVIDING A PERFORATED COVER, PORCELAIN COATING THE PERFORATED COVER AND THEREAFTER ATTACHING SAID PORCELAIN COATED COVER TO SAID SHELL BY PASSING SAID TABS THROUGH THE PERFORATIONS IN SAID COVER AND THEN BENDING THE TABS ALONG THE REDUCED CROSS SECTION OVER ONTO THE COVER SO AS TO HOLD SAID COVER IN PLACE RELATIVE TO SAID BAFFLES.
 2. IN THE METHOD OF CLAIM 1, THE STEP OF PLACING AN AUXILIARY SEALING MEMBER ON THE PERFORATED COVER TO SURROUND THE TABS, PRIOR TO BENDING THE TABS, WHEREBY AS THE TABS ARE BENT THEY ARE FORCED AGAINST THE AUXILIARY SEALING MEMBER TO SECURE IT TO THE COVER AND AGAINST THE TABS. 